A valve seat grinding apparatus is disclosed in U.S. Pat. No. 4,287,688. As disclosed, the present invention is a combination of the kind as disclosed in this patent and, accordingly, the patent is hereby incorporated by reference. The above referenced Ser. No. 650,851 has of record the presently known prior art pertaining to valve grinding apparatus, including German GM No. 8303975 (1983). Also of record in the application Ser. No. 650,851 is Ser. No. 705,869, filed Feb. 28, 1985, which at present has been allowed but not yet issued. The disclosed ball component incorporated into the present invention is an adaptation of a small specimen of a flexible shaft torque transfer coupler understood to be commercially available in Germany.